1/*
2 * Copyright 2011 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#ifndef SkEmptyShader_DEFINED
9#define SkEmptyShader_DEFINED
10
11#include "SkShader.h"
12
13// TODO: move this to private, as there is a public factory on SkShader
14
15/**
16 *  \class SkEmptyShader
17 *  A Shader that always draws nothing. Its createContext always returns NULL.
18 */
19class SK_API SkEmptyShader : public SkShader {
20public:
21    SkEmptyShader() {}
22
23    size_t contextSize() const override {
24        // Even though createContext returns NULL we have to return a value of at least
25        // sizeof(SkShader::Context) to satisfy SkSmallAllocator.
26        return sizeof(SkShader::Context);
27    }
28
29    SK_TO_STRING_OVERRIDE()
30    SK_DECLARE_PUBLIC_FLATTENABLE_DESERIALIZATION_PROCS(SkEmptyShader)
31
32protected:
33    SkShader::Context* onCreateContext(const ContextRec&, void*) const override {
34        return NULL;
35    }
36
37    void flatten(SkWriteBuffer& buffer) const override {
38        // Do nothing.
39        // We just don't want to fall through to SkShader::flatten(),
40        // which will write data we don't care to serialize or decode.
41    }
42
43private:
44    typedef SkShader INHERITED;
45};
46
47#endif
48